1. Field of the Invention
This disclosure is related to the field of polymer interlayers for multiple layer panels and multiple layer panels having at least one polymer interlayer sheet. Specifically, this disclosure is related to the field of special effect metal pigments for use in polymer interlayers and polymer interlayers comprising special effect metal pigments
2. Description of Related Art
Multiple layer panels are generally panels comprised of two sheets of a substrate (such as, but not limited to, glass, polyester, polyacrylate, or polycarbonate) with one or more polymer interlayers sandwiched therebetween. The laminated multiple layer glass panels are commonly utilized in architectural window applications and in the windows of motor vehicles and airplanes. These applications are commonly referred to as laminated safety glass. The main function of the interlayer in the laminated safety glass is to absorb energy resulting from impact or force applied to the glass, to keep the layers of glass bonded even when the force is applied and the glass is broken, and to prevent the glass from breaking up into sharp pieces. Additionally, the interlayer may, among other things, give the glass a much higher sound insulation rating, reduce UV and/or IR light transmission, or enhance the aesthetic appeal of the associated window. The interlayer may be a single layer, a combination of two or more single layers, a multilayer that has been coextruded, a combination of at least one single layer and at least one multilayer, or a combination of multilayer sheets. In regard to the photovoltaic applications, the main function of the interlayer is to encapsulate the photovoltaic solar panels which are used to generate and supply electricity in commercial and residential applications.
Laminated safety glass, or multiple layer glass panels, is used in many different applications in the transportation industry, including automotive, railroad, and aviation vehicles. Polymer interlayers used in laminated safety glass have also been used in architectural or building applications as, for example, panels for windows in buildings or stadiums, balustrades, decorative panels (such as in offices), and the like. Such applications allow additional creativity by incorporating color and other decorative features into a design.
There is a need for improved interlayers for use in the windows and other panels where a metallic appearance is desirable. There is also a need for improved interlayers with a visible surface texture or appearance. There is also a need for interlayers having a metallic appearance that can be used in combination with other interlayers, such as other colors, to provide more colors and appearances in laminated glass panels. There is also a need for interlayers for use in glass panels to provide privacy boundaries between adjacent rooms or areas. There is also a need for glazings, and particularly colored glazings, having a metallic type reflection to provide near infrared absorbance to reduce solar heat load from the environment.
Interlayers for windshields and other multiple layer glass panel applications are generally produced by mixing a polymer resin (or resins) such as poly(vinyl butyral) with one or more plasticizers and other additives and melt processing the mix into a sheet by any applicable process or method known to one of skill in the art, including, but not limited to, extrusion. For multiple layer interlayers comprising two or more layers, the layers may be combined by processes such as co-extrusion and lamination. Other additional ingredients may optionally be added for various other purposes. After the interlayer sheet is formed, it is typically collected and rolled for transportation and storage and for later use in the multiple layer glass panel, as discussed below.
Contemplated polymer interlayers include, but are not limited to, poly(vinyl)acetal resins such as poly(vinyl butyral) (PVB), polyurethane (PU), poly(ethylene-co-vinyl acetate) (EVA), polyvinylchloride (PVC), polyethylenes, polyolefins, ethylene acrylate ester copolymers, poly(ethylene-co-butyl acrylate), silicone elastomers, epoxy resins and any acid copolymers and ionomers derived from any of the foregoing possible thermoplastic resins. Multilayer laminates can include multiple layer glass panels and multilayer polymer films. In certain embodiments, the multiple polymer films in the multilayer laminates may be laminated together to provide a multilayer film or interlayer. In certain embodiments, these polymer films may have coatings, such as metal, silicone or other applicable coatings known to those of ordinary skill in the art. The individual polymer films which comprise the multilayer polymer films may be laminated together using an adhesive as known to those of ordinary skill in the art.
The following offers a simplified general description of the manner in which multiple layer glass panels are generally produced in combination with the interlayers. First, at least one polymer interlayer sheet (single or multilayer) is placed between two substrates and any excess interlayer is trimmed from the edges, creating an assembly. It is not uncommon, particularly in architectural and/or building applications such as windows in buildings, interior or exterior panels, balustrades, and the like, for multiple polymer interlayer sheets or a polymer interlayer sheet with multiple layers (or a combination of both) to be placed within the two substrates creating a multiple layer glass panel with multiple polymer interlayers. Then, air is removed from the assembly by an applicable process or method known to one of skill in the art; e.g., through nip rollers, vacuum bag or another deairing mechanism. Additionally, the interlayer is partially press-bonded to the substrates by any method known to one of ordinary skill in the art. In a last step, in order to form a final unitary structure, this preliminary bonding is rendered more permanent by, for example, a high temperature and pressure lamination process known to one of ordinary skill in the art such as, but not limited to, autoclaving, or by other processes known to one of ordinary skill in the art.
One of the problems in the manufacture of multilayer laminate glass panels is the presence of various optical defects in the final unitary structure or laminate, such as the window or panel. The multiple layer glass panels need to be free of optical defects and have consistent color or tone. Additionally, the multiple layer glass panels need to be aesthetically pleasing, that is, the glass panels cannot have flow lines or other undesirable manufacturing defects. It is important to maintain the high optical standards when adding new features and functionality to the glass panels.
Optical quality defects such as flow lines, inconsistent pigmentation, and other defects such as (but not limited to) extruded contamination and inconsistent sheet thickness and/or surface roughness are common problems in the field of multiple layer glass panels. Good optical quality is particularly important where the multiple layer glass panels are those used in applications which require higher levels of optical or visual quality, such as windows. In an attempt to improve the multiple layer glass panels used in windows and other glazing applications, and particularly in an attempt to make them more aesthetically pleasing to the consumer, new colors and features are constantly being developed. One attempt to improve the technology is the use of additional colors and/or pigments in the window or panel, such as metallic pigments. Using a metallic pigment in an interlayer has potential advantages over interlayers without metallic pigments, such as the ability to provide additional colors as well as reflectivity and other features, however, the use of the metallic pigments results in other unfavorable sacrifices, including, but not limited to, uneven distribution of the pigments on and/or in the interlayer, poor optical quality or visual defects, poor (too high or too low) adhesion, and increased manufacturing costs (i.e., the costs associated with producing the multilayer interlayer as well as the cost of the pigment). The use of metallic pigments in an interlayer also eliminates the need to use a metallic film either laminated in the panel or applied to a glass laminate panel to provide the reflectivity and other properties. The use of metallic pigments in an interlayer may also provide some near infrared reflectance and absorbance to reduce the solar heat load from entering a building. Accordingly, there is a need in the art for the development of an interlayer having a special effect metal pigment that provides an interlayer having a metallic color and reflective appearance as well as a textured surface without a reduction in optical, mechanical, and performance characteristics of an interlayer.